Conventionally, taking advantage of their features of being thin and consuming low power, liquid crystal display devices have been widely used as displays for office automation (OA) equipment such as personal computers and portable information equipment such as cellular phones and personal digital assistants (PDAs).
A liquid crystal display device includes a thin film transistor (TFT) substrate, a counter substrate opposed to the TFT substrate, and a liquid crystal layer sealed with a rectangular frame-shaped sealing material between the TFT substrate and the counter substrate.
In the counter substrate, a common electrode layer and the like are formed on the side thereof facing the TFT substrate. In the TFT substrate, a plurality of interconnects including a plurality of source lines, a plurality of gate lines, a common interconnect for supplying a signal to the common electrode layer, and the like are formed. The TFT substrate often has a layered insulating film including an inorganic insulating film and an organic insulating film stacked one upon the other to cover the plurality of interconnects described above.
Since the TFT substrate and the counter substrate are fixed to each other with a sealing material, it is desirable to provide high adherence of the sealing material to the TFT substrate and the counter substrate.
For example, for enhancing the adherence of the sealing material to the TFT substrate, Patent Document 1 discloses a method in which an organic insulating film is partly removed to allow a sealing material to adhere directly to an inorganic insulating film that is comparatively high in adherence to the sealing material.